Gas spring



H. HAMPEL ETAL GAS SPRING Filed Aug. 17, 1964 Y FIG* 1.

L Nvguror. s

3/ m// /m u Nov. 22, 1966 Hema.. HAMPEL ERNST wsreN HAGSN- ATfy S.

United States Patent The invention relates to a gas spring.

Apart from pendulum clocks, metal springs are predominently used as the driving element for mechanically actuated clocks. Metal springs have the disadvantage that the force which they give olf is not uniform and depends on the tension of the spring, that is to say, the force is greater or less according to how much the clock is wound up. In order to keep this undesirable force difference within certain limits and to make compensation easier by appropriately regulating the working of the clock, about 15 to 25% of the spring tension is left unused on each side. It is also known that certain steps have to be taken to lessen the danger of clock springs breaking.

The present invention aims to avoid these disadvantages and to provide means for driving clockwork or the like mechanisms which operate reliably, are simple in construction and which discharge a force which virtually always remains constant over a relatively long period of time.

This object is achieved -according to the invention, by a gas spring with a substantially horizontal characteristic in which the force required for driving is provided by the exhaust force of the plunger `of the gas spring.

It is desirable for the longitudinal operative movement of the plunger directly or indirectly to produce a rotary movement.

A substantially horizontal characteristic can be obtained if the volume of gas enclosed in the gas chamber of the gas spring is large in relation to the volume displaced by the plunger; that is to say, the gas chamber is either large in diameter relative to the plunger or is considerably longer than is actually necessary for the stroke.

Instead of or as well as the measures described for obtaining a substantially horizontal characteristic, the gas chamber may be connected to a container supplying an additional volume of gas, the container communicating with the gas chamber through a capillary tube. The plunger may be in the form of a differential piston and have toothing in one -or both portions positioned outside the gas chamber; the toothing preferably serves to translate the longitudinal movement into a rot-ary movement.

In theory it is of course possible to use a plunger moving in and out only on one side of the gas chamber, or a plunger in the form of a piston mounted on a piston rod which may also have toothing on its portion located permanently outside the gas chamber. However, it is particularly advantageous to use a differential piston in gas springs, provided according to the invention to drive clockwork or the like mechanisms, since in spite of the relatively small exhaust force required a high gas pressure can be applied, for the difference in diameter between the two parts of the differential piston can be compartively small so that the active surface of the piston, and thus the exhaust force, is also small.

In order that the invention may be well understood there will now be described one embodiment thereof, given by way of example only, reference being had to the accompanying drawings, in which:

FIG. 1 diagrammatically illustrates a gas spring for driving a clockwork =or the like mechanism; and

FIG. 2 diagrammatically illustrates a clockwork mechanism driven by the gas spring of FIG. 1.

For the sake of clarity, parts, etc., which are not essential to an understanding of the invention have been omitted.

The plunger of a gas spring has a virtually constant exhaust force in all positions only if the characteristic of the spring is substantially horizontal, that is to say, if the maximum compression ratio is as small as possible, preferably not greater than about 1.3. The maximum compression ratio is commonly defined by the fraction V1:V2, in which V1 represents the total volume of gas with the compressor completely extended and V2 the total volume of gas with the compressor -completely retracted.

In this embodiment, a substantially horizontal cha-racteristic is obtained by connecting the gas chamber 1 to a container 2 supplying an additional volume yof gas, the connection preferably being made through a capillary tube 3. This is understood as being a tube of which the internal width is very small in relation to the wall thickness. The advantage of such a pipe or tube is that it can easily be bent to suit the conditions obtaining, without thereby creating a kink which would inhibit or even prevent the gas from flowing through. Moreover, it can easily be fixed to any desired place, for example by soldering.

Further, the plunger 4 of the gas spring is a differential piston with toothing 6 and/ or 7 on one or both portions permanently located outside the spring housing 5. The toothing comes into engagement with the corresponding toothed wheel -of the clockwork, so that upward, longitudinal operative movement of the plunger 4, under the pressure of gas previously created in the chamber 1 by downward displacement of the plunger, is converted into a rotary movement. It is desirable for a clutch locking mechanism such as a ratchet or tree-wheel means to be arranged between the toothing 6, 7 and the corresponding toothed wheel of the clockwork. In this way the longitudinal movement accompanying the winding-up of the gas spring, which is done by inserting the plunger 4 into the spring housing 5, is not transmitted t-o the clockwork.

In the case of cl-ocks, particularly those which need not be wound daily, it would be highly desirable to have an indication of the working reserve. With conventional spring mechanisms such an indication cannot be given without extra expense and for this reason is not generally provided.

The working reserve can easily be indicated if a pin 8 is mounted on the plunger 4 so that it is always outside the spring housing 5. The pin may, for example, extend through a slot in a rear wall of the clock (not shown) and indicate the working reserve still in hand by its position in relation to suitable markings.

It may sometimes be desirable, instead of having the working reserve indicated directly by the pin 8, to let the pin 8, possibly with a gear interposed, actuate a pointer, a disc or the like, unless it is preferred to use one of the toothings 6, 7 for this purpose. The -advantage of this would be that the working reserve would be clearly indicated even if the total stroke of the gas spring were very small.

Referring now to FIG. 2, the toothing 6, upon the upward operative movement of the plunger 4, acts through the previously mentioned clutch locking mechanism, e.g. a rachet 9 and pawl 9a, to actuate the drive wheel 10 of the driving system of a clockwork mechanism. A spiral spring 12 is fixed to the shaft of the balance wheel 11 and keeps the wheel swinging to and fro. A pin 13 connected to the balance wheel 11 entrains the pallet 14 at every movement. The pallet has a pivot bearing at 15. Each of the pallet hooks 16 frees one tooth of the escapement wheel 17, whereby the balance wheel 11 receives a new rotary impulse. The balance wheel generally swings to and fro five times per second, i.e., the second hand makes iive small movements forward per second. The shaft 18 of the escapement wheel is driven by the drive wheel 10. The drive for the minute and hour wheel is also taken from the shaft 18. At 19, are small setting screws used to balance the balance wheel 11, which is generally in two parts.

The gas spring can be mass produced with constant dimensions for a Wide variety of clockworks, for if the plunger 4 is required to have a larger or smaller exhaust force this can easily be provided by making the gas pressure in the gas chamber 1 (and thus in the container 2) correspondingly higher or lower.

y The gas spring also has the two great advantages of remaining effective Without rewinding for a longer time than a comparable clock spring and, secondly, of having a long working life, since the Wear to which its parts are subjected is almost negligible.

We claim:

1. A clockwork or like mechanism comprising a mechanical escapement mechanism, a gas spring and drive means connecting said escapement mechanism and said gas spring, said gas spring comprising an elongated housing containing gas, a cylindrical plunger operating in opposed openings in said housing, said plunger having a first portion extending through one said opening and ter- 10 2. A mechanism according to claim 1, wherein a container supplying an additional volume of gas is connected to said housing `by a capillary tube.

References Cited by the Examiner 15 UNITED STATES PATENTS 598,982 2/1898 Egger 267-1 1,289,712 12/1918 Evans 73-1468 2,716,451 s/1955 Taylor 164-110 20 2,749,700 6/1956 seiigman sas-42 3,059,342 10/1962 Beal 33-2055 3,064,628 11/1962 canaiizo etai. 121-48 RICHARD B. WILKINSON, Primary Examiner.

25 LEO SMILLOW, Examiner.

G. F. BAKER. Assistant Examiner. 

1. A CLOCKWORK OR LIKE MECHANISM COMPRISING A MECHANICAL ESCAPEMENT MECHANISM, A GAS SPRING AND DRIVE MEANS CONNECTING SAID ESCAPEMENT MECHANISM AND SAID GAS SPRING, SAID GAS SPRING COMPRISING AN ELONGATED HOUSING CONTAINING GAS, A CYLINDRICAL PLUNGER OPERATING IN OPPOSED OPENINGS IN SAID HOUSING, SAID PLUNGER HAVING A FIRST PORTION EXTENDING THROUGH ONE SAID OPENING AND TERMINATING WITHIN SAID HOUSING, A SECOND PORTION OF SAID PLUNGER OF LESS DIAMETER THAN SAID FIRST PORTION RIGIDLY SECURED TO THE INNER END OF SAID FIRST PORTION AND EXTEND- 